I'd love to see a gamified email system. Reputation points for writing clear, concise emails. Negative points for forwards, rambling meaningless emails, accidental reply-alls... what a world it could be.

When Joel Spolsky and I set out to design the Stack Exchange Q&A engine in 2008 – then known as Stack Overflow – we borrowed liberally and unapologetically from any online system that we felt worked. Some of our notable influences included: Reddit and Digg voting Xbox 360 achievements Wikiped...